use super::*;
use crate::scene::{DebugDrawList, DebugIndex as Index, DebugVertex as Vertex};
use crate::storage::GpuVec;
use crate::viewport::ViewportInfo;
use crate::RenderLayouts;
use parking_lot::RwLock;

pub struct FrameData {
    vertices: GpuVec<Vertex>,
    indices: GpuVec<Index>,
}

pub struct DebugPass {
    device: Arc<wgpu::Device>,
    pipeline: wgpu::RenderPipeline,
    target_info: ViewportInfo,
    draw_list: RwLock<DebugDrawList>,
}

impl DebugPass {
    pub fn new(
        device: Arc<wgpu::Device>,
        layouts: Arc<RenderLayouts>,
        target_info: ViewportInfo,
    ) -> Self {
        // TODO hook into ShaderStore system
        let shader = device.create_shader_module(wgpu::include_wgsl!("debug_shader.wgsl"));

        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("DebugPass Pipeline Layout"),
            bind_group_layouts: &[&layouts.bind_viewport],
            push_constant_ranges: &[],
        });

        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("DebugPass Pipeline"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: "vs_main",
                buffers: &[Vertex::desc()],
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: "fs_main",
                targets: &[Some(wgpu::ColorTargetState {
                    format: target_info.output_format,
                    blend: Some(wgpu::BlendState::REPLACE),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
            }),
            primitive: wgpu::PrimitiveState {
                topology: wgpu::PrimitiveTopology::LineList,
                strip_index_format: None,
                front_face: wgpu::FrontFace::Ccw,
                cull_mode: None,
                polygon_mode: wgpu::PolygonMode::Fill,
                unclipped_depth: false,
                conservative: false,
            },
            depth_stencil: Some(wgpu::DepthStencilState {
                format: target_info.depth_format,
                depth_write_enabled: false,
                depth_compare: wgpu::CompareFunction::Less,
                stencil: Default::default(),
                bias: Default::default(),
            }),
            multisample: wgpu::MultisampleState {
                count: 1,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            multiview: None,
        });

        Self {
            device,
            pipeline,
            target_info,
            draw_list: Default::default(),
        }
    }

    pub fn add_draw_list(&self, draw_list: &DebugDrawList) {
        self.draw_list.write().merge(draw_list);
    }
}

impl RenderPass for DebugPass {
    type FrameData = FrameData;

    fn create_frame_data(&self) -> FrameData {
        FrameData {
            vertices: GpuVec::new(
                self.device.clone(),
                wgpu::BufferUsages::VERTEX,
                1024 * 1024,
                Some("Debug Vertex Buffer".to_string()),
                false,
            ),
            indices: GpuVec::new(
                self.device.clone(),
                wgpu::BufferUsages::INDEX,
                1024 * 1024,
                Some("Debug Index Buffer".to_string()),
                false,
            ),
        }
    }

    fn begin_frame(&self, data: &mut FrameData, phases: &mut Vec<Phase>, queue: &wgpu::Queue) {
        phases.push(Phase::Overlay);

        use std::mem::replace;
        use std::ops::DerefMut;

        let mut draw_list_lock = self.draw_list.write();
        let vertices = replace(&mut draw_list_lock.vertices, Default::default());
        let indices = replace(&mut draw_list_lock.indices, Default::default());

        let _ = replace(data.vertices.deref_mut(), vertices);
        let _ = replace(data.indices.deref_mut(), indices);

        data.vertices.write(queue);
        data.indices.write(queue);
    }

    fn record_render(&self, data: PhaseData<&FrameData>) -> Option<wgpu::RenderBundle> {
        let mut cmds =
            self.device
                .create_render_bundle_encoder(&wgpu::RenderBundleEncoderDescriptor {
                    label: Some("DebugPass Render Bundle"),
                    color_formats: &[Some(self.target_info.output_format)],
                    depth_stencil: Some(wgpu::RenderBundleDepthStencil {
                        format: self.target_info.depth_format,
                        depth_read_only: false, // TODO optimize?
                        stencil_read_only: true,
                    }),
                    sample_count: 1,
                    multiview: None,
                });

        let vertices = &data.frame_data.vertices;
        let indices = &data.frame_data.indices;

        cmds.set_pipeline(&self.pipeline);
        cmds.set_bind_group(0, data.bind_viewport, &[]);
        cmds.set_vertex_buffer(0, vertices.as_ref().slice(..));
        cmds.set_index_buffer(indices.as_ref().slice(..), wgpu::IndexFormat::Uint32);

        let index_range = 0..(indices.len() as u32);
        cmds.draw_indexed(index_range, 0, 0..1);

        Some(cmds.finish(&wgpu::RenderBundleDescriptor::default()))
    }
}